Sulfur Use in Western MN, What We Know and What We Don t

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1 Sulfur Use in Western MN, What We Know and What We Don t Daniel Kaiser Associate Professor Department of Soil, Water and Climate U of M Twin Cities dekaiser@umn.edu 2018 Agvise Soil Fertility Seminars

2 Sulfur s Role in Plants Macronutrient used in similar amounts as phosphorus for many crops Component of amino acids Cysteine Methionine Sulfur is important for nitrate reduction in plants Deficiency slows down the formation of amino acids and other proteins Sulfur influences nitrogen function and utilization in plants Influences photosynthesis HRSW removes ~0.1 lb of S per bushel produced, Corn ~0.05 lb of S per bushel

3 Source: IPNI

4 Corn Sulfur Guidelines for Minnesota Broadcast sulfur to apply (lbs S per acre) 0-6 Soil Organic Matter Rotation >4% Corn-Corn Corn-Soybean Sandy Soils For high residue corn on corn systems

5 Sulfur Response Yield responses are increasing-why? Sulfate deposition have decreased ~ 5-10 lb/ac/yr in the last 30+ years Sulfur in fertilizer sources (other than S fertilizers) and pesticides have decreased Less manure More crop residue What is the most important factor? Two key factors: soil temperature and organic matter concentration

6 Microbial process Source: IPNI

7 Step 1: What Crops Respond to Sulfur

8 Results S Source x Rate Study In-season S rate (lb s/ac) In-season S rate (lb s/ac) Soil Grain Yield 12% Fine ab 14.5b 14.7a Sand 95.5ab 96.0a 94.4b Pre-plant S did not increase grain yield or protein concentration of Glenn Side-dress AMS did increase grain yield (P<0.10) Some discussions with producers if the lack of response was due to us using a high protein variety Would the effect be different for a variety like LCS-Albany or Faller? Results are inconclusive on potential for response to S

9 HRSW Data Summary Staples Var. No S +S No S +S YLD (bu/ac) PRO (%) Faller Glenn May RB Select Vant Avg. 74b 77a 17.4b 17.8a Crookston, Kimball, FF Var. No S +S No S +S YLD (bu/ac) PRO (%) Faller Glenn May RB Select Vant Avg

10 Grain Yield Response to S Applied Prior to Corn in a C-SB Rotation Sulfur Location C1 SB1 C2 SB2 C3 SB3 --Yield Increase bu ac Red Wing Rochester Becker Lamberton Responses of interest: Response at Lamberton (C1) was likely due to residue from the previous corn crop Lack of response at Becker may be due to sulfate in the irrigation water

11 Net Return over the 6-yr Rotation due to P, K, or S Red Wing Rochester Nutrient Rate 2 yr 4 yr 6 yr Total 2 yr 4 yr 6 yr Total lb/ac $/acre Phosphorus Potassium Sulfur P rates are in lb P 2 O 5 /ac /lb K rates are in lb K 2 O/ac $0.40.lb S - $0.50/lb Corn $4/bu Beans $10/bu Applied P and K rate may not be the optimum rate for each site Application cost is not factored into net return

12 P-K-S Study Red Wing, MN 6/23/15 + S No P 218 bu/ac No P or S 167 bu/ac + P No S 210 bu/ac + P & S 235 bu/ac

13 Response to P PKS Study P response at Red Wing in spite of very high soil tests Measured total S in P sources % (4.7 lbs S applied with P trt) DAP 1.2% MAP 1.8% Response to S in P source at Red Wing would explain response Trifoliate S was increased for S treatments but not for P S in the P source was sufficient to increase corn yield but did not carry over

14 Sulfur and Grain Yield Alfalfa, corn, and canola are more likely to show a strong response to S Small grain crops may respond on eroded ground with the best responses on sandy low organic matter fields I would avoid direct application to soybean N + P + S can stimulate vegetative growth Sulfur can deplete over time in deficient soils responses may get greater

15 Step 2: Select the Right Source of Sulfur

16 Sources of Sulfur Thiosulfate Ion Not Plant Available Dissociates into elemental S And Sulfate Sulfate Ion Plant Available

17 Elemental Sulfur Availability Microbial mitigated process Bacteria and Fungi Soil temperature and moisture affect oxidation of S to SO 4 2- Optimum around o F Oxidation is limited by the surface area of the fertilizer source Larger particles oxidize slower

18 Net S Days To Soil Series Increase 50% Ox Max. Ox % of Applied days Barnes Bearden Canisteo Clarion Colvin Cordova Estherville Fargo Formdale Hegne Hubbard Lester Mt Carrol Nicollet Normania Okaboji Pierz Seaton Storden Tara Verndale Ves Waukegan Webster Wheatville Zimmerman S Mineralized (ug day -1 ) Oxidation of Elemental S 90 o F Sulfur Mineralization Rate from SOM Verndale Zimmerma Hubbard Bearden MtCarrol Hegne Wheatvil Okaboji Fargo Pierz Formdale Canisteo Nicollet Barnes Ves Waukegan StordenWebster Clarion Tara Seaton Esthervi Normania Lester Cordova y=0.02(som) P<0.01 R 2 = Soil Organic Matter Concentration (%)

19 2-Year Average Yield Fall vs Spring: Elemental & Sulfate-S S Rate (lb/ac) Yield (bu/ac) 0 232b 5 235a a a Summary 4 locations No evidence of an effect of Fall vs Spring application on yield No difference between sources Rate was significant with 5 lbs S producing the maximum yield

20 Strategy for use of Elemental S Elemental S will not provide any available in the early growing season following a spring or fall application This would include MES-10, MES-15, and MEZ which the elemental S is more finely ground Oxidation is more likely in July and August Repeated application of elemental S may supply plant available S due to sulfate carried over from one year to the next Add sulfate with elemental S for early season availability ATS is a good option

21 Step 3: Where/When/Why do Sulfur Responses Occur?

22 Pathway for loss Large Storehouse of potentially available S Source: IPNI

23 Fall 2011 Red Wing, MN Fall 2012 Fall 2013 Fall " b a 6-12" b a b a 12-24" b a b a b a Soil SO 4 -S (ppm) Soil SO 4 -S (ppm) Soil SO 4 -S (ppm) Soil SO 4 -S (ppm) No S + 25 lb S

24 Leaching of Sulfur The rate of S leaching depends on soil texture Sandy soils are more likely to require annual applications Sulfate-S can remain in the upper soil profile for 1 or more years Fall application of sulfate may be okay in high clay soils Leaching of sulfate-s is not fast enough to warrant split application of S

25 C:S Ratio of Corn Stover Year Location No Sulfur + Sulfur 2011 Red Wing 580:1 500:1 Rochester 691:1 630: Becker 560:1 524:1 Lamberton 531:1 495: Red Wing 572:1a 490:1b Rochester 590:1a 497:1b 2014 Becker 794:1 853:1 Lamberton 1340:1a 666:1b Immobilization occurs when > 400:1; mineralization occurs when < 200:1

26 Fe Deficient Corn?? Renville, MN June No S No Fe 155 bu/ac + S No Fe 168 bu/ac + S + Foliar Fe 171 bu/ac 2015 No Fe 223 bu/ac GPA Redline 221 bu/ac SOM > 5.0%

27 Red Wing, MN 2015 Becker, MN 2014 Red Wing, MN 2015

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29 2-Year Average Yield Fall vs Spring: Elemental & Sulfate-S S Rate (lb/ac) Yield (bu/ac) 0 232b 5 235a a a Summary 4 locations No evidence of an effect of Fall vs Spring application on yield No difference between sources Rate was significant with 5 lbs S producing the maximum yield

30 Sulfur Response Scenarios 1:Low S supply capacity Response is dictated by supply capacity of soil i.e. organic matter Temp. and moisture are still factors If deficient, S uptake will be limited throughout the growing season Plant analysis should provide useful data 2:Temporary deficiency Response is dictated by availability of S at key growth stages Greater impact of temp. and moisture Start and end of season Plant may green up if S supply increases Plant tissue analysis would be less reliable

31 Key Growth Stages for Sulfur Uptake in Corn ~40% Of total uptake ~50% Of total uptake ~10% Of total uptake Source: Bender et al., 2013

32 Sulfur Studies Corn Grain Yield Red River Valley Sulfur Rate -lb S/ac- Marshall 2014 Norman 2014 Norman 2015 Polk yr-Avg Bushels/acre b ab ab a 189 Statistical Significance P>F ns ns ns 0.09 ns

33 Wrap Up I don t think sulfate leaching is a serious issue to warrant only applying elemental S Timing of S application was not discussed but data indicates that S application can be delayed up through V5 with no yield penalty for corn Soil and plant tissue tests for S are not reliable for determining where a response will occur Some striping can occur on plants early in the growing season which may not affect grain yield

34 Are Responses to S Increasing? The answer depends on early season rainfall and soil temperature Atmospheric S has decreased but the relative impact in an individual year is low May compound over a number of years Mineralization of S from soil organic matter is still an important source of S Rate depends on soil temp and moisture Drainage may also impact S availability

35 When to Apply S Sulfate can carry over in soils so the question of Fall versus Spring application is less important Should you apply sulfur across all acres? Probably not needed in all circumstances but a low rate may be warranted No justification to apply over 20 lbs on medium to fine textured soils Apply to low organic matter or highly leached soils Poorly drained soils may also warrant application Soil test for S??? Responses may be limited to highly alkali areas Source of sulfur applied is important

36 Thank You Questions? Daniel Kaiser University of Minnesota